I have been looking at the manuals (user and service) of the A3, A30 and AJ and have made some notes of the differences. I then tried to relate the differences by comparing the amps schematics, but there are too many variables for a newcomer like me to explain the specifications. I hope you guys can give me a hand.

Rails are about the same:
A3 and A30: 25V
AJ 24V

whatever Pa was in mood to write down ; take them all as typical FW PSU , based on 2x18Vac secondaries

I understand the higher gain of the A30 is due to the input stage. Is this correct?
20db is practically same as 19,6db ; 20db means 10x , while 19,6db means 9,55x ; difference is probably result of convenient resistor values , with intention of staying in gain ballpark

Question:
If A3 and A30 both have each channel drawing 100W, should total consumption not be similar?

again - different info originated from different places/instances where Pa wrote those numbers ; you can't expect of him to be serious all the time
channel power draw is same thing as channel power consumption
in Pa's world 50W of heat up or down is no big fuss

Active output stage biased by current source at
A3 slightly greater than 2 amps
A30 slightly less than 2 amps
AJ not given

Question:
What causes the difference between 4 Ohm output of A3 and A30? I assume it is the "slightly greater" and "slightly less" than 2A bias that is the cause. Is this assumption correct?

Question:
How come the AJ has so much lower power into 4 Ohm? I assumed that, since total power consumption is similar, bias must be similar.

ask Papa to rewrite FW product table , in case of AJ
difference between A3 and A30 - different Aleph CCS AC gain , I resume ( frankly - by memory only , lazy to compare schematics right now ........... again ....... and again ........ and again ... , same as different treshold for current clamp/limit - small bjt hidden around Rs in lower half of output stage

Max output
A3 23V 8A
A30 25V 5A
AJ 21V 2.5A

Questions:
What causes the relative large difference between A3 and A30?
Are the numbers for the AJ correct? If so, why so different from A3 and A30?

AJ - I think Pa mislead us with these 12,5W/4R ......... but frankly - I didn't looked too much in original AJ circ , regarding that issue - it was and still is irrelevant for my intentions
whatever - it's easy to make it as "usual" - Aleph having at least 30% more power on 4 , than on 8 ohm load

use most potent one (current wise) ,as basic schm , then put your fave input (probably Jfets , cascoded or not ) , adequate number of outputs ( more pairs if spks are current hungrier) , with less intrusive current limiter

or toss it entirely - as is tossed in J2

Pa is trying all the time to give us a recepies , not 15 , OUPS - 10 ( ) God's Commandments ........

use most potent one (current wise) ,as basic schm , then put your fave input (probably Jfets , cascoded or not ) , adequate number of outputs ( more pairs if spks are current hungrier) , with less intrusive current limiter

or toss it entirely - as is tossed in J2

Pa is trying all the time to give us a recepies , not 15 , OUPS - 10 ( ) God's Commandments ........